Understanding the effect of response rate and class size interaction on students evaluation of teaching in a higher education

Figures & data

Table 1. Descriptive statistics of students’ evaluation of instructors according to class size and response rate at UOD

Response rate	Class size	Mean	Std. deviation	N
Low response rate	Small class size	3.88	1.07	12,937
	Medium class size	3.88	1.07	30,880
	Large class size	3.89	1.08	21,710
	Total	3.88	1.07	65,527
Medium response rate	Small class size	3.92	1.03	16,094
	Medium class size	3.90	1.01	26,916
	Large class size	3.97	1.03	28,428
	Total	3.93	1.02	71,438
High response rate	Small class size	3.96	0.98	14,311
	Medium class size	4.00	0.94	8,483
	Large class size	3.96	0.98	8,815
	Total	3.97	0.97	31,609
Total	Small class size	3.92	1.03	43,342
	Medium class size	3.91	1.03	66,279
	Large class size	3.94	1.04	58,953
	Total	3.92	1.03	168,574

Table 2. Two-Way ANOVA summary table where the dependent variable is students’ evaluation of instructors and the independent variables are response rate and class size

Source	Sum of squares	df	Mean square	F	Sig.	Partial eta squared
Response rate	167.584	2	83.792	78.437	.000	.001
Class size	12.037	2	6.019	5.634	.004	.000
Response rate × Class size	41.116	4	10.279	9.622	.000	.000
Error	180,073.198	168,565	1.068
Total	2,773,328.395	168,574

Table 3. Pairwise comparisons showing the mean difference in the rating of students’ evaluation of instructors between different response rates

(I) Response rate	(J) Response rate	Mean difference (I–J)	Std. error	Sig.
Low response rate	Medium response rate	−.047	.006	.000
	High response rate	−.089	.007	.000
Medium response rate	Low response rate	.047	.006	.000
	High response rate	−.042	.007	.000
High response rate	Low response rate	.089	.007	.000
	Medium response rate	.042	.007	.000

Table 4. Pairwise comparisons showing the mean difference in the rating of students’ evaluation of instructors between different class sizes

(I) Class size	(J) Class size	Mean difference (I–J)	Std. error	Sig.
Small class size	Medium class size	−.009	.007	.192
	Large class size	−.023	.007	.001
Medium class size	Small class size	.009	.007	.192
	Large class size	−.014	.007	.037
Large class size	Small class size	.023	.007	.001
	Medium class size	.014	.007	.037

Figure 1. The interaction between response rate and class size on rating of students’ evaluation of instructors.

Table 5. Descriptive statistics of students’ evaluation of courses according to class size and response rate at UOD

Response rate	Class size	Mean	Std. deviation	N
Low response rate	Small class size	3.66	1.09	12,937
	Medium class size	3.69	1.12	30,880
	Large class size	3.71	1.11	21,710
	Total	3.69	1.11	65,527
Medium response rate	Small class size	3.73	1.07	16,094
	Medium class size	3.76	1.05	26,916
	Large class size	3.79	1.06	28,428
	Total	3.77	1.06	71,438
High response rate	Small class size	3.73	1.04	14,311
	Medium class size	3.88	0.98	8,483
	Large class size	3.81	1.01	8,815
	Total	3.79	1.02	31,609
Total	Small class size	3.71	1.07	43,342
	Medium class size	3.74	1.08	66,279
	Large class size	3.76	1.07	58,953
	Total	3.74	1.07	168,574

Table 6. Two-Way ANOVA summary table where the dependent variable is students’ evaluation of courses and the independent variables are response rate and class size

Source	Sum of squares	df	Mean square	F	Sig.	Partial eta squared
Response rate	311.279	2	155.640	135.456	.000	.002
Class size	118.806	2	59.403	51.700	.000	.001
Response rate × Class size	72.856	4	18.214	15.852	.000	.000
Error	193,681.231	168,565	1.149
Total	2,556,210.120	168,574

Table 7. Pairwise comparisons showing the mean difference in the students’ evaluation of courses between different response rates

(I) Response rate	(J) Response rate	Mean difference (I–J)	Std. error	Sig.
Low response rate	Medium response rate	−0.071	.006	.000
	High response rate	−0.118	.008	.000
Medium response rate	Low response rate	0.071	.006	.000
	High response rate	−0.047	.007	.000
High response rate	Low response rate	0.118	.008	.000
	Medium response rate	0.047	.007	.000

Table 8. Pairwise comparisons showing the mean difference in the students’ evaluation of courses between different class sizes

(I) Class size	(J) Class size	Mean difference (I–J)	Std. error	Sig.
Small class size	Medium class size	−.068	.007	.000
	Large class size	−.058	.007	.000
Medium class size	Small class size	.068	.007	.000
	Large class size	.010	.007	.149
Large class size	Small class size	.058	.007	.000
	Medium class size	−.010	.007	.149

Figure 2. The interaction between response rate and class size on rating of students’ evaluation of courses.

Table 9. Suggested response rate for different class sizes while conducting the students’ evaluation of instructors and courses

Class size	Response rate
	Low	Medium	High
Small		☒	☑
Medium			☑☒
Large		☑☒

Notes: ☑: Recommended response rate and class size required to evaluate instructors.

☒: Recommended response rate and class size required to evaluate courses.